Techniques for managing the migration of virtual machine instances are described herein. A migration of a first virtual machine instance is started by preparing an appropriate target location to receive the first virtual machine instance. Next, a second virtual machine instance at the target location is enabled by first copying state information from the first virtual machine instance to the second virtual machine instance, by next creating connections between the second virtual machine instance and resources associated with the first virtual machine instance, and by finally starting packet forwarding between the two virtual machine instances. Finally, the first virtual machine instance is locked, the copy is finalized, and the second virtual machine instance is started.